The network began as a seismology research project, to track earthquakes in this fault-ridden part of the world. But as technologies developed, the network became more sophisticated, gathering far more data than ever before. Eventually, the science of earthquake observation reached a tipping point, and became the science of earthquake prediction.

Richard Allen, director of the UC Berkeley Seismology Laboratory, now has a prototype app on his computer called ShakeAlert that emits an annoying clanging noise up to a minute before an earthquake hits his office. Most of these quakes are so small you can barely perceive them, but ShakeAlert has successfully issued warnings in advance of all three of the quakes that hit the Bay Area in the past year. And, though a minute warning may not seem like much, it’s enough time to stop a train, pull over on the freeway, initiate shutdown at a power station, or stabilize a patient in surgery. It’s the kind of warning that could be a gamechanger for people in earthquake country.